1. Field of the Invention
The present invention relates to an information processing apparatus and a television tuner and, in particular, to an information processing apparatus and a television tuner that are suitable for users to view a digital television program using an analog television set.
2. Description of the Related Art
Widely used analog television sets receive broadcast signals of an analog television program and allow the users to enjoy looking at and listening to video and sound based on the broadcast signals.
Such television sets perform a predetermined demodulation process on broadcast signals, generate analog video signals and audio signals, and supply the video signals to a display unit, such as a cathode ray tube. Thus, video is displayed. In addition, the television sets amplify the audio signal and supply the audio signal to a speaker. Thus, sound is output from the speaker.
In recent years, in order to increase the resolution of a video image and the quality of audio sound, provide a better service about a program, and efficiently use frequency bands, digital television programs have been broadcasted.
A television broadcast signal in a digital format (hereinafter referred to as a “digital broadcast signal”) can be received by a television tuner based on a digital technique (hereinafter referred to as a “digital tuner”). However, it is difficult for a television tuner based on analog technique (hereinafter referred to as an “analog tuner”) to receive a digital broadcast signal.
Accordingly, a technique for converting a digital broadcast signal into a television broadcast signal in an analog format (hereinafter referred to as an “analog broadcast signal”) and supplying the analog broadcast signal to a television set has been developed (refer to, for example, Japanese Registered Utility Model No. 3119745 and, in particular, FIG. 2).
In this technique, a television set including an analog tuner allows users to view video and listen to sound extracted from a digital broadcast signal by acquiring a converted analog signal. Hereinafter, this technique is referred to as a “first method”.
In addition to the first method, a technique for using a television set as only a monitor device by simultaneously using a television broadcast receiver (i.e., a set top box) including a digital tuner has been developed. Hereinafter, this technique is referred to as a “second method”.